A common problem associated with the use of internal combustion engines is the formation of undesirable byproducts found in the exhaust stream, particularly nitrogen-oxides. After-treatment systems, such as selective catalytic reaction (SCR) systems, are used to lower the nitrogen-oxide content in the exhaust stream using urea and a reduction catalyst. In some SCR systems a urea decomposition reactor with a mixer is used to promote the decomposition of the urea into ammonia.
While detachable decomposition reactors within a SCR system are known, a majority of conventional decomposition reactors are typically formed as an integral part to the SCR system or are external reactors that are welded directly to the SCR system. Also, the reactor itself is formed by welding both an injector mount and a mixer directly to the inner tube of the decomposition reactor. As a result, conventional decomposition reactors suffer from poor heat retention within the reactor and are formed with welding distortions that result in the formation of reductant deposits within the reactor.